Milne-like spacetimes were found by investigating low regularity aspects of Lorentzian geometry. This is a growing field with many tantalizing problems to solve. For low regularity causal theory, generalizations, and various results, see [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}. For low regularity spacetime inextendibility results, see [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}. For the singularity theorems in low regularity, see [15]}, [16]}, [17]}, [18]}. For results in geodesics and maximizing causal curves in low regularity, see [19]}, [20]}. For results in Lorentzian length spaces, see [21]}, [22]}, [23]}, [24]}, [25]}. Lastly, for results related to the null distance function and other notions of distance defined on a spacetime, see [26]}, [27]}, [28]}, [29]}.

